This invention relates generally to a system and apparatus for controlling the flow of fluid to and from a surgical handpiece, and more particularly, to a handpiece used in ophthalmic surgery.
A number of techniques have been proposed for removing cataracts. One is described in an article by Aziz Y. Anis entitled, "Illustrated Step-by-Step Description of the Anis Dry Extra Capsular Cataract Extraction Technique with In-the-Bag Lens Implementation", Seminars in Ophthalmology, v. 1, N. 2, June 1986, pp. 113-129. Another technique is generally referred to as the phaco-emulsification technique disclosed in U.S. Pat. No. 3,693,613 to Kelman et al. In this latter approach, the cataract lens is fragmented and the fragmented lens tissue is aspirated. In both techniques, the anterior chamber of the eye is maintained at substantially the normal shape with a fluid. Moreover, it is desirable to control the amount of fluid dispensed by surgical instruments of the latter type It is common to control irrigating fluid to a surgical handpiece, such as used in ophthalmic surgery by a separate and relatively large control console that has a manually positionable switch movable to a plurality of positions or an automatic control loop/system. Another known kind of surgical handpiece is described in U.S. Pat. No. 4,764,165, in which part of the liquid dispensing apparatus is attached to the handpiece itself. In this apparatus a micro-motor controls dispensing of the fluid from the handpiece in response to operation of a foot-controlled mechanism.
Still another kind of technique and associated surgical handpiece for removing cataracts is described in U.S. Pat. No. 4,908,015, entitled, "Cataract Removal Technique", issued to Aziz Y. Anis. In this approach for removing cataraots, a hydrosonics handpiece instrument is utilized. In this latter handpiece, ultrasonic energy can be selectively applied to an operative probe extending from the handpiece housing. The probe when ultrasonically vibrated is used to mechanically penetrate the cataract lens. After or during ultrasonic energy application, however, treating fluid is metered into the eye through a fluid passage in the probe. Various kinds of medical treating fluids are supplied therethrough by a syringe being inserted into a passage which communicates with the probe passage. In this approach, small amounts of fluid, for example, between 1/500 and 1/100 a milliliter are used so as to separate the layers of the lens cortex and lens nucleus for achieving desired cataract removal. However, because a surgeon must control both the handpiece and a syringe when injecting the fluid, there is usually less than entirely satisfactory control of the instrument during the operative procedure.